The objective of this study is to determine the usefulness of the short-term use of naltrexone in 1) reducing opiate use; 2) reducing craving for opiates; 3) increasing therapeutic contact; and 4) enhancing the adequacy of psychosocial functioning. Sixty male opiate patients will be used as subjects and will be randomly assigned to one of three experimental groups: 1) naltrexone (20); 2) placebo (20); 3) clinic contact only (20). Subjects will receive naltrexone, placebo, or clinic contact only daily for two weeks, as outpatients. After two weeks administration of naltrexone/placebo and daily clinic contact will be discontinued and all subjects will be followed weekly for the following six weeks and then monthly for four months. Differences and patterns of differences among the three experimental groups in patterns of opiate and other drug use, treatment contact, perceived need for opiates, and psychosocial functioning will be compared at a number of points in time.